Standardization - two independent implementations are good. [LWN.net]

Standardization - two independent implementations are good.

Posted Sep 2, 2024 22:40 UTC (Mon) by viro (subscriber, #7872)
In reply to: Standardization - two independent implementations are good. by ralfj
Parent article: Rust-for-Linux developer Wedson Almeida Filho drops out

When specification is "whatever the interpreter actually does", you get wonders like sh(1). Which is _not_ a good language to write in...

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Standardization - two independent implementations are good.

Posted Sep 5, 2024 11:41 UTC (Thu) by taladar (subscriber, #68407) [Link] (3 responses)

Which is why there is an effort to develop a Rust spec but that still doesn't require a second implementation, just a test suite that checks if the one implementation conforms to the spec.

2nd Implementation tests the meaning of the specification

Posted Sep 7, 2024 17:10 UTC (Sat) by jjs (guest, #10315) [Link] (2 responses)

That test suite can determine if one implementation meets what the spec writers interpret the spec to mean. It can't detect if the spec always means what the spec writers think it means (the wonders of human language). The purpose of a second implementation is to check that the wording of the spec actually only means what the spec writers think it means. I.e. catch unseen errors in the spec. Again, there's a reason IETF requires two independent implementations of an RFC before they declare it a standard.

2nd Implementation tests the meaning of the specification

Posted Sep 7, 2024 17:40 UTC (Sat) by intelfx (subscriber, #130118) [Link]

Or you can simply have one team write the compiler (and maybe the spec) and some other team to write the tests using the spec.

2nd Implementation tests the meaning of the specification

Posted Sep 8, 2024 12:02 UTC (Sun) by farnz (subscriber, #17727) [Link]

That's where two implementations of the test suite comes in handy, since you now have two separate groups of people who've read the specification and agree on what it means; where one test suite fails and the other passes, you need to resolve that by either fixing the specification, or getting the passing test suite to agree that they had a gap in test coverage.